The present invention relates to a noise cancellation circuit, an analog signal processing circuit, and an electronic instrument.
When noise is mixed into a signal of an electronic circuit, malfunction, deterioration in characteristics, and the like occur due to the noise. Noise is mixed through various paths such as a signal line connecting electronic circuits or a power supply line of an electronic circuit.
JP-A-6-188729 discloses technology in which noise superimposed on a power supply voltage transmitted through a power supply line is removed using a low-pass filter disposed between a power supply and ground.
However, in order to completely remove high-frequency noise using the technology disclosed in JP-A-6-188729, it is necessary to form a filter using a capacitor with a large capacitance. This results in an increase in parts cost and module size. For example, a circuit area of 1 to 4 mm2 is required when forming a capacitor with a capacitance of 40 microfarads on a substrate.
A minute alternating-current component called a power supply ripple is contained in a power supply, and may cause the characteristics of an electronic circuit to deteriorate. Since the power supply ripple generally has a low frequency, the power supply ripple cannot be removed using the technology disclosed in JP-A-6-188729 which utilizes a low-pass filter.